Disruptions in sensory processing contribute significantly to the morbidity associated with diseases such as Alzheimer's Disease or following a neurological stroke, yet the neural basis of this processing is poorly understood. The division of the olfactory system used by mice to recognize pheromones provides examples of the basic tasks of sensory processing, but carried out in a set of neural structures that are anatomically simpler and more accessible than most mammalian sensory systems. The limited number of processing locations separating stimulus transduction and behavioral output make this system particularly useful for exploring the mechanisms by which sensory systems extract information about the salient characteristics of natural stimuli, and represent them in a form that can be used to guide behavior. Measuring the activity of the second order neurons of this system during the presentation of natural stimuli has the potential to test a number of hypotheses about how such mechanisms are implemented in the olfactory system. The activity of this cell population will be measured through extracellular recordings. [unreadable] [unreadable] [unreadable]